The directivity of information flow through a channel was defined by Massey [1]} in the form of directed information. The author shows that in the presence of feedback, this is a more useful quantity than the traditional mutual information. From a similar perspective, the TE measures the information flow from one process to another by quantifying the deviation from the generalized Markov property as a Kullback–Leibler distance, thus both TE and the directed information can be used to estimate the directional informational interaction between two random variables.
